1. Field of the Invention
The present invention relates to a cathode ray tube and a method of forming a phosphor screen of the cathode ray tube.
2. Description of the Related Art
As a color cathode ray tube of high contrast, there is known a color cathode ray tube in which a glass panel forming a part of a cathode ray tube body, i.e., a panel having a phosphor screen formed on its inner surface is made of a dark glass having a transmittance of about 40 to 50% or a color cathode ray tube in which such a phosphor screen is employed that has formed on its inner surface a so-called pigment phosphor using a pigment whose color is the same color of the phosphor deposited on phosphor particles.
In the former color cathode ray tube in which the panel is formed of the dark glass, an external light is absorbed by the dark glass so that a contrast thereof can be increased. At the same time, however, a light emitted from the phosphor screen also is absorbed by the dark glass so that a brightness thereof is lowered.
In the latter cathode ray tube in which the phosphor screen is formed by using the pigment phosphor, an external light is absorbed by the pigment so that a contrast thereof can be increased. In this case, however, phosphor particles of several layers (e.g., three to four layers) are laminated to form the phosphor screen. As a result, a light from the phosphor particle is partly absorbed by the pigment with the result that a brightness thereof is lowered 10 to 15%.